Forced air furnace having scroll type heat exchanger



Deco E2, 1950 F. R. HIGLEY FORCED AIR FURNACE HAVING SCROLL TYPE HEAT EXCHAWGER 3 Sheets-Sheet 1 Original Filed Jan. 26, 1942 P ZZ INVENTOR.

5i ATTORNEY5 FIE NK E. ///6L 74 Deco 12 1950 F. R. HlGLEY FORCED AIR FURNACE HAVING SCROLL TYPE HEAT EXCHAN GER ori in-afixmed Jan. 26, 1942 3 Sheets-Sheet 2 INVENTOR.

Hen/YA A. H/GLEY dflwzd am M ATTORNEYS DecQ 12 1950 F. R. HIGLEY 2,533,458

FORCED AIR FURNACE HAVING SCROLL TYPE HEAT EXCHANGER Original Filed Jan. 26, 1942 3 Sheets-Sheet 5 INVENTOR Patented Dec. 12, 1950 FORCED AIR FURNACE HAVING SCROLL TYPE HEAT EXOHANGER Frank R. Higley, Cleveland Heights, Ohio, as signor, by mesne assignments; to Aifiliated Gas Equipment, Inc., Cleveland, Ohio, a corporation of Delaware Substituted for abandoned application Serial No. 428,206, January 26, 1942. This application filed February 8, 1946, Serial No. 646,241

2 Claims. 1

This invention relates to improvements in forced air furnaces, particularly forced air furnaces embodying blowers of the heated volute type. This application is a substitute for application Serial No. 428,206 filed January 26, 1942, by this applicant and held to have become abandoned. v v

One of the objects of the invention is the provision of a furnace of the character stated which shall be of light weight and low cost.

Another object is the provision of a furnace of this character having a heat transfer member of high conductivity over which air is directed at high velocity.

Another object is to limit the cast or extruded portion of the furnace to a relatively small part of the whole, the remaining parts being constructed of sheet material.

Another object is the provision of a heating unit of which one volute wall portion is a casting with either the inner or the outer surfaces or both such surfaces extended, for example finned, sheet material being utilized in connection with such casting to complete the combustion chamber and a conductor for combustion gases extending upwardly therefrom.

Another object is to confine the casting to a part of the scroll of less than 180 curvative in order that its production as a casting may be relatively simple.

Still another object is the provision, in addition to the wall casting above mentioned, of a fine connection casting which may be rigidly joined to the wall casting with machined meeting surfaces so that they become functionally the equivalent ofa single casting but are more easily and more economically produced.

A further object is the provision of a cleanout door in the smaller of said castings so positioned as to be accessible from the exterior of the furnace casing to serve the gas conductor passage.

Still another object is the provision of a furnace of the character stated having a fan driving motor so located as not to require any additional casing space and to be in a relatively cool spot well above floor level.

Other objects and features of novelty will appear as I proceed with the description of that embodiment of the invention, which, for the purposes of the present application, I have illustrated in the accompanying drawings, wherein:

Fig. 1 is a view of a furnace embodying the invention, taken generally as inside elevation but with the near casing panel cut away, and certain other parts removed as will hereinafter appear;

Fig. 2 is a view of the same taken as from the top with the top wall panel cut away.

Figs. 3 and 4 are horizontal sectional detail views on a larger scale, the sections being taken substantially on the lines 3-3 and 4-4 of Fig. 1; and

Fig. 5 is a fragmental detail sectional view corresponding to a portion of Fig. 4 but on a still larger scale.

Fig. 6 is a horizontal sectional view through the lower part of the heater taken on the line B-6 of Fig. 1 showing side plates l5 and back plate 23 extending to the floor or base of the heater.

In the drawings the casing side and end walls of the furnace are indicated generally by the reference numbers ill and II), respectively, and the top by the number ll. Within the casing there is a blower, the scroll of which consists partly of a casting or the like which is heated, so that air moved over the scroll by the blower wheel will be heated.

The blower wheel is shown at 12 and comprises a shaft l3 which is mounted in bearings supported by brackets M that are attached to the side walls l5 of the blower housing, which may be of sheet material, preferably sheet metal, these side plates being provided with openings l6 through which air may enter the housing.

On one side of the blower there is a casting I! which constitutes part of the blower scroll and its extension. This casting has side flanges [8 to which the sheet metal side plates l5 are attached by means of bolts or other fastenings l9, the joints bein sealed as by asbestos packing 20. The fastenings l9 also pass through one flange of each of a series of angle bars 2| to which are welded balile plates 22 that bridge the space between the blower housing and the side walls H! of the casing. These bafiles extend from the top of casting l1 down to a point marked B on Fig. 1. There is preferably a single baflle plate on each side of the blower, but there may be a series of angle bars 2| arranged end to end and positioned to approximate the curve of the scroll.

The lower edges of the side plates 15 of the blower housing rest upon the floor or base of the furnace as will be clear from Fig. 6 of drawings. Their rear edges are vertical and are welded to a back plate 23 which also rests upon the floor or base of the furnace. These plates l5 and 23 toether with the lower portion of the casting 17 including a depending apron 24 form the combustion chamber 25 of the furnace. The upper part o the casting together with the walls as 3 and 23 form a conductor for hot gases. That part of the casting which forms a wall of the gas condoctor is positioned parallel to or substantially parallel to the back plate 23.

The blower scroll portion on the side opposite the casting ii is formed of sheet material, preferably sheet metal, as indicated at 25. Its lower edge is secured to the cast part of the scroll by suitable fastenings, as shown at 2'5. and its side edges are welded to the side plates 55 of the housing. A burner, such as a gas burner 28, is positioned within the combustion. chamber and this chamber has a suitable supply of atmos pheric air admitted through a port 2% in the casing to complete combustion. This chamber in which substantially atmospheric pressure is maintained must be separated from the of the casting space outside the blower where a slight vacuum exists because of the blower action. Consequently the lower end of apron 2a is connected by a partition Sii with the casing end wall 16, and baiiies 3! are caused to extend from the side plates i 5 to the casing side walls i=3.

Air from the blower is conducted out of the furnace through delivery extension 22 formed by a continuation of side plates It, a short back plate 33 secured to the upper end of casting ll by screws 34 or the like, and a front plate the plates 33 and 35 being welded to the side plates It. with scroll section 26, but the latter may extend beyond the lower edge of plate 35 for a short di tance as indicated in Fig. 1 to constitute the cutoff for the scroll.

At one end of shaft !3 there is a pulley 35 which is connected by a belt 3'5 with an electric motor 38 which is adjustably mounted upon a bracket 3d, these parts being so arranged and disposed that the motor occupies space relatively near the shaft :3 in the angle formed between wall 35 and the radially innermost part of scroll section 26. This location for the motor is particularly advantageous since the motor thereby occupies an elevated position out of the way of possible damage in the event of water collecting above the floor of a basement or other compartments where the furnace is installed, and more particularly because this location requires no extension of the furnace casing horizontally. In other words, the motor occupies space which otherwise would be wasted.

While in some aspects of the invention the rigid part ll of the scroll may be formed otherwise than as a casting, as, for example, an extrusion product, I prefer to form it as a casting. When so formed, I provide it with exterior fins 50 and interior fins -H. The exterior fins it; terminate a distance below the top of the casting. They are deepest at their upper extremities and gradually decrease in depth throughout the curved part of the casting down to the part overlying the burner 28. In fact, their depth preferably decreases to zero at the lower end of the casting. Fins d'i are deepest at the lower end of the casting and gradually decrease in depth upwardly therefrom. The lower end of the casting is subjected to the greatest heat. by radiation as well as by conduction. It is important. therefore, that the fins 46 at this point be of minimum depth in order to avoid burning of the metal, as well as to save useless weight. T-ligher up and especially in the hot gas conductor these fins are deeper in order to absorb maximum heat from the products of combustion. On the inner side the fins 4! on the lower end of the casting are of maxi- Plate 35 extends down to and is connected 4 mum depth in order to provide large surface for dissipating the extreme heat of the casting at this point. Further along up the scroll the inner do not need to be so deep, and because of the high speed of travel of the air over the scroll at these points, short fins extend the inner surface sufficiently to transmit all the heat absorbed by the deep outer fins 49.

The upper end of the back surface of casting ll above fins 49 is machined to receive a machined surface on a second casting 42 which is suitably securedto casting I! as by means of screws 43. Casting 42 is hollow. It has a forvard portion 44 which is rectangular in horizontal section and merges into a round pipe 45 which projects upwardly through the casting top H. The rectangular part 44 as shown herein is substantially flush with the casing top H and has a cover or cleanout door 46 which may be removed to permit a cleaning brush to be projected downwardly through the hollow casting into the hot gas conductor. Portions of the end surfaces of the rectangular part 44 of this casting are machined flush with the machined flanges it of casting i! so that the side plates l5 may make good joints with the casting, suitable fastenings 41 being employed for the purpose. The upper end of back plate 23 is also attached by suitable fastenings to the lower end of the rectangular portion 44 of'the flue connection casting.

Across the casing behind the blower and behind the vbafiles 22 there is a horizontal partition 48 which defines an air chamber 49 communieating with the air, intake opening 50. This partition has an opening 5! therethrough which clears the back wall 23 of the blower housing and so much of the side walls I 5 as extend behind the bafiles 22. A pair of air filters 52 are positioned within the chamber .49, extending upwardly to the casing top H, with their lower edges resting on the partition 48 behind the opening 5|. Their inner edges meet each other in the center of .the chamber and their outer edges meetv the side walls Ill of the casing. As indicated by arrowsin the drawings, the incoming air from the opening 58 must, therefore, pass through these filters, after which it wipes against the casting 42 including the. flue connection 45 and against the backand side walls of, the hot gas conductor. Thereafter it flows downwardly through theopening 5 I, thence over the side plates [5 of the hot gas conductor and the combustion chamber, past the lower edges of the bafiies 22, these lower edges terminating substantially at B in Fig. 1, and then into the lower inlet openings [6.

The operation of the furnace will be clear to those skilled in the art from the above descrip-. tion of the apparatus. efficient type of heater and one which is extremely compact.v There are few joints between the air and gas. conductors and any leakage. which does occur is from the air conductor into the gas conductor owing to the pressure differ-- ential between the two. The use of a casting as one wall only of the-combustion chamber and the hot gas conductor, and confining the condoctor to one side onlyof the blower, reduce the weight of the furnace to a minimum. Also the curved part of the casting is thus confined to an angle of less than thereby permitting the simplest of molding operations without the use of cores, and facilitating the formation of fins. The

metal employed iorjthe-casting may be ferrous.-

It constitutes a highly metal or metals of higher conductivity. Aluminum, for example, may be employed to advantage, and since the casting weight is low, the cost of an assembly embodying aluminum is not prohibitive.

I claim: I

1. In a heater including a blower of the volute type, a burner, a cast scroll wall extending over and then straight upwardly away from the burner, a cast flue connection attached to and extending from the outer face of the upper end of said scroll wall, side plate means extending from the top to the bottom of said heater, connected to said scroll wall to form sides of a combustion chamber for said burner in the lower part of said heater, and extending rearwardly beyond said scroll wall in the direction of said flue connection, and back plate means eXtending between said side plate means, from the bottom of the heater to the cast flue connection, to form the back of said combustion chamber and a flue passage leading upwardly therefrom to said flue connection.

2. In a heater including a blower of the volute type, a burner, a cast scroll wall extending over and then straight upwardly away from the burner, a cast flue connection attached to and extending from the outer face of the upper end of said scroll wall, side plate means extending from the top to the bottom of said heater, connected to said scroll wall to form sides of a combustion chamber for said burner in the lower part or saidgheater, and extending rearwardly beyond said scroll wall in the direction of said iiue connection, and back plate means extending between said side plate means, from the bottom of the heater to the cast flue connection, to form the back of said combustion chamber and a flue passage leading upwardly therefrom to said flue connection, said flue connection having a cleanout opening in its upper side in line with said flue passage.

' FRANK R. HTIGLEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,519,673 Doble Dec. 16, 1924 1,877,905 Le Grand Sept. 20, 1932 2,215,519 Anderson Sept. 24, 1940 2,222,080 Lattner Nov. 19, 1940 2,258,790 Murphy Oct. 14, 1941 2,275,358 Glasby Mar. 3, 1942 

